Coolant pump with heat sinking to coolant

ABSTRACT

A vehicle coolant pump with heat protection for the internal electronics and circuit boards for operation of the coolant pump. Gap fillers positioned adjacent said electronics and circuit boards transfer heat to the coolant fluid in the engine.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims benefit of U.S. Patent Application62/024,492 filed on Jul. 15, 2014.

TECHNICAL FIELD

The present invention is related to vehicle coolant pumps, and moreparticularly to improved coolant pumps with heat protection.

BACKGROUND

Coolant pumps for circulating cooling fluids in vehicles and othercooling systems are in constant use today. There are various types ofcoolant pumps, most of which work to various degrees of satisfaction.

Some coolant pumps contain electrical systems and/or electromagneticcomponents and systems, and thus contain heat sensitive electroniccomponents, such as circuit boards. This is particularly true with dualmode coolant pumps that may contain both electric motors andelectromagnetic mechanisms. If the electrical and electronic componentsand systems are not maintained within conventional operatingtemperatures, the coolant pumps could be ineffective or fail.

There is thus a need to provide coolant pumps with improved methods ofprotecting electric or electronic components and systems from excessiveheat.

SUMMARY OF THE INVENTION

It is an objective of the present invention to provide an improvedcoolant pump that meets these needs and provides benefits and advantagesover known coolant pumps.

In a preferred embodiment of the invention, a dual mode coolant pump isprovided which selectively rotates an impeller in a coolant fluidhousing. The dual mode coolant pump includes housings in which anelectric motor drive mechanism and a mechanical drive mechanism forrotating the impeller are positioned. The coolant fluid housing isattached to the vehicle engine and has an inlet port for receipt ofcoolant fluid and an outlet port for transfer of the coolant fluid intothe engine block.

The electric motor, which preferably is a brushless DC motor, and theelectromagnetic clutch mechanism for the mechanical drive mechanism areboth operated electrically. A circuit board (CB) is located in thecoolant pump housing adjacent the coolant fluid housing, and containselectronic components for operating the electric motor andelectromagnetic clutch mechanism. Power is supplied from the vehicleelectrical systems, including an electronic control unit (ECU). Ifelectrical power is absent, the electric motor can be powered by thevehicle battery.

A gap filler is positioned in the pump housing adjacent to, and incontact with, the circuit board. The gap filler acts as a heat sink andtransfers heat from the circuit board and its components through thepump housing and into the coolant fluid. Since typically the coolantfluid is at a temperature lower than the temperatures of the circuitboard components, this embodiment of the invention protects the heatsensitive electronic components by maintaining them within theiracceptable temperature limits.

Further embodiments of the invention as well as additional features andbenefits of the invention will be disclosed below in the followingwritten description and accompanying drawings, together with theappended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts an embodiment of the invention.

FIG. 2 is an exploded view of the embodiment of FIG. 1.

FIG. 3 is a cross-sectional view of the coolant pump depicted in FIG. 1.

FIG. 4 schematically depicts a cooling system and an associated controlsystem relative to an embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A perspective view of an embodiment of the present invention 10 is shownin FIG. 1, and an exploded view is depicted in FIG. 2. The embodimentincludes a dual mode coolant pump 20 and an impeller housing 30. Theimpeller housing 30 is adapted to be connected to, or at least be influid communication with, a vehicle engine block 40.

The coolant pump 20 includes a motor housing 22, an electric motor 24, asolenoid housing 26, a friction clutch mechanism 33 (as better shown inFIG. 3) and a pulley member 29. The pulley member 29 is adapted to berotated by an engine belt. An engine belt for this purpose is shown inFIG. 4 and designated by reference number 31. The engine belt is alsoattached to a pulley member 32 positioned on the vehicle engine block40. The pulley member 29 is rotated by the engine at a speed (“inputspeed”) determined by a pulley ratio.

The coolant pump 20 is depicted in cross-section in FIG. 3. A preferreddual mode coolant pump that can be utilized with the present inventionis disclosed and discussed in detail in U.S. patent application Ser. No.14/149,683, filed on Jan. 7, 2014, and entitled “Accessory Drive WithFriction Clutch and Electric Motor”, the disclosure of which is herebyincorporated herein by reference.

An electric motor 24 is positioned in the motor housing 22. The motorhousing is preferably made of a metal material with good thermalconductivity, such as aluminum. The electric motor is preferably abrushless DC motor, and includes a coil-type stator member 25 and arotor member 27. The rotor member is fixedly attached to central pumpshaft member 28.

A solenoid member 34 is positioned in the solenoid housing 26. Thesolenoid housing is preferably made of a metal material, such as lowcarbon steel.

The electronics for electric motor 24 and solenoid member 34 arecontained in the circuit board (“CB”) 50. The circuit board contains theelectronic components which electrically control the operation of theelectric motor and the solenoid member, including turning them on andoff. Power from the circuit board 50 is supplied to the electric motor24 through lead frame 52, and to the solenoid member 34 through leadframe 57.

Electric power to the circuit board 50 is supplied through connectormember 60 (shown in FIGS. 1 and 2). The connector member 60 has aplurality of lead wires that are connected to the circuit board. Thelead wires include two wires which provide power to the circuit boardand a plurality of other wires which are signal wires to provide signalsto operate the electric motor and solenoid member. The circuit board 50is connected to the motor housing 22 by a plurality of fasteners, suchas screw members 53.

Positioned between the circuit board 50 and the inside wall of the motorhousing is a gap filler member 55. The filler member conducts heat fromthe circuit board into the aluminum motor housing 22 where the heat inturn is distributed to the coolant fluid which is being circulated inthe impeller housing 30.

The gap filler member 55 can be any conventional type for providing heattransfer between a CB heat source and a heat sink surface. Gap fillerstypically are soft materials with low durometers and which have goodthermal conductivity. Gap fillers can be used to fill gaps between hotcomponents. The materials can be flexible with an elastic nature and canblanket uneven surfaces, either individually or in layers or groups. Inthe present invention, heat is conducted away from the circuit board 50by the gap filler 55 and into the aluminum motor housing 22 where theheat is conducted to the cooler coolant fluid. Typically in vehiclecooling systems, the coolant fluid has a maximum temperature of about129° C., while most circuit board components have a rated temperature of150° C. or higher.

The wall 72 of the motor housing 22 faces and is in contact with thecoolant fluid. The wall 72 has a plurality of fluid recesses or pockets70, and can be individual recesses or annular grooves. Some of therecesses 70 are shown in FIG. 3. Any number of recesses, pockets orgrooves can be provided. These items 70 make the motor housing wall 72thinner in spots, places or areas, which assists in transferring orconducting heat from the circuit board 50 and gap filler 55 into thecoolant fluid. Preferably the thickness of the motor housing wall in thebottoms of the recesses is about five to twenty millimeters (5-20 mm)This is represented by distance D in FIG. 3. The surfaces at the ends ofthe recesses, pockets, grooves, etc. should be as thin as possible inorder to aid in transferring heat from the circuit board, but withoutsacrificing the integrity and durability of the motor housing wall 72 orthe motor housing itself.

The coolant pump shaft 28 is positioned centrally in the housings 22 and26, with the electric motor 24 and friction clutch mechanism 33 beingpositioned in axial alignment around the shaft 28. An impeller member 80is connected to impeller shaft 29 which is connected at one end 28A ofthe coolant pump shaft 28. The impeller member 80 and impeller shaft 29protrude from the motor housing and extend into the interior of theimpeller housing 30.

The impeller housing 30 is made of a metal material, such as aluminum,and has a central cavity 90, an inlet port 92 for inlet of coolantfluid, and an outlet port (not shown) for passage of the coolant fluidinto the engine block 40. When the impeller 80 is rotated by the dualmode coolant pump 20, the coolant liquid is pumped through the outletinto and through the engine and the rest of the engine cooling system,and then returned to the coolant pump inlet port 92.

In an alternate embodiment of the invention, a coolant control valve(CCV) can also be provided. Coolant control valves control the directionand amount of flow of the coolant as it enters the engine block.

As indicated above, the rotor 27 of the electric motor 24 is fixedlyattached to the coolant pump shaft 28 and rotates with it. When themotor is activated, the shafts 28 and 29, as well as the impeller member80, rotate. The rotation of the impeller member causes the coolant fluidto flow through the impeller housing and the rest of the coolant system.

Preferably, the coolant pump shaft 28 is rotated by the electric motorfor most of the period in which a coolant pump is needed. Whenadditional coolant flow is required, such as when the vehicle pulls aheavy load and more cooling is required, the pump shaft 28 is rotatedmechanically at input speed. For this purpose, the solenoid member 34 isdeenergized which allows armature member 110 to shift axially away fromthe solenoid. This allows the friction lining member 112 on the springbiased friction plate 114 to contact the cover member 116. Since thecover member 116 is attached to the pulley member 29 and rotates withit, this provides rotation of the coolant pump shaft at input speed. Thecomponents, including the solenoid member, armature member, frictionplate, friction linings and biasing spring members are collectivelycalled a friction clutch mechanism 33.

Under normal operation when the coolant pump shaft and impeller arebeing rotated by the electric motor, the solenoid member 34 iselectrically activated. This attracts the armature member 110, which ismade of a magnetic metal material and prevents the friction plate 114from being biased against the cover where the friction linings 112 onthe friction plate 114 can contact the inside surface of the covermember and cause mechanical rotation of the shafts 28 and 29 and theimpeller 80.

The coolant pump shaft 28 is mounted in the housing and allowed torotate by a pair of bearing members 120 and 122. The electric rotor 27is positioned on the shaft 28 between the two bearing members 120, 122.

The pulley member 29 is mounted in the coolant pump by bearing member124 and allowed to rotate freely around the friction clutch mechanism.The armature member 110 is biased in the coolant pump by a plurality ofcoil spring members 130. Additional details of the structure of the dualmode coolant pump and its operation are contained in U.S. patentapplication Ser. No. 14/149,683, the disclosure of which is incorporatedherein by reference.

FIG. 4 depicts a preferred system and process for operating the coolantpump 20 and a vehicle cooling system 130 in accordance with the presentinvention. The coolant pump 20 is a dual mode coolant pump and includesan electric motor 24, and a friction clutch mechanism 33. The mechanism33 in combination with a pulley member 29 comprise a mechanical drive“M”. The dual mode coolant pump 20 rotates an impeller member 80 in theimpeller housing 30.

The operation of the coolant pump 20 is operated by control logic 140which receives appropriate data and information from an engineelectronic control unit (“ECU”) 142. The engine ECU 142 receives dataand information from one or more temperature sensors 150, other engineand vehicle sensors 152, as well as control instructions and signalsfrom a vehicle ECU 160. The ECUs and control logic operate the coolantpump 20 and impeller rotation to maintain the temperature of the coolantfluid within acceptable limits.

Coolant fluid from the coolant pump 20 flows into and through the engine40. The coolant fluid then exits the engine and flows through a heatexchanger 184 such as a radiator, where it is cooled. The temperature ofthe coolant can be read by a thermostat 190. Following flow through theheat exchanger, the cooler coolant fluid is then returned 186 to thecoolant pump 20.

The present invention provides an improved coolant pump and enginecooling system that not only maintains the coolant fluid withinappropriate temperature limits, but also maintains the temperature ofthe coolant pump electronics and circuit board within their appropriatetemperature limits. This provides a coolant pump and cooling systemwhich is efficient, durable, and long-lasting.

Although the invention has been described with respect to preferredembodiments, it is to be also understood that it is not to be so limitedsince changes and modifications can be made therein which are within thefull scope of this invention as detailed by the following claims.

What is claimed is:
 1. A cooling system for a vehicle engine,comprising: (a) a coolant pump, said coolant pump comprising a drivemechanism and a driven mechanism with said drive mechanism comprising amechanical drive mechanism, and said driven mechanism comprising anelectric motor, said electric motor positioned in a motor housing; (b) acontrol system for operating said coolant pump, said control systemcomprising at least one temperature sensor, an ECU, and a circuit board;and (c) a gap filler positioned in said motor housing and in contactwith said circuit board; wherein heat from said circuit board istransferred through said gap filler and said motor housing, and into acoolant fluid.
 2. The cooling system as described in claim 1 whereinsaid coolant pump is a dual mode coolant pump.
 3. The cooling system asdescribed in claim 1 wherein said electric motor is a brushless DCmotor.
 4. The cooling system as described in claim 1 wherein said motorhousing has at least one wall member which is positioned between saidcircuit board and the coolant fluid, and wherein said gap filler ispositioned between said at least one wall member and said circuit board.5. The cooling system as described in claim 1 wherein a plurality ofrecesses are provided in a first side of said at least one wall memberwhich is in contact with a coolant fluid, and wherein said gap filler ispositioned on the opposite side of said first side of at least one wallmember.
 6. The cooling system as described in claim 5 wherein the wallthickness in bottoms of said recesses is about 5 to 20 millimeters. 7.The cooling system as described in claim 1 further comprising a shaftmember and an impeller member, said shaft member being selectivelydriven by said drive mechanism and said driven mechanism.
 8. The coolingsystem as described in claim 7 wherein said shaft member is supported insaid coolant pump by a pair of bearing members, and said electric motoris positioned between said bearing members.
 9. The cooling system asdescribed in claim 1 wherein operation of said coolant pump iscontrolled at least in part by control logic.
 10. The cooling system asdescribed in claim 1 wherein said mechanical drive mechanism includes asolenoid member and a friction clutch member.
 11. The cooling system asdescribed in claim 10 wherein activation of said solenoid memberprevents said mechanical drive member from rotating said shaft member.12. The cooling system as described in claim 10 wherein activation ofsaid solenoid members allows said mechanical drive member to rotate saidshaft member.